Laser light has a characteristic that it is reflected from a white substance but absorbed by a black substance. When it is irradiated to the skin surface of a human body, it is easily absorbed by melanin present in the skin. A principle of laser depilation irradiates laser light to cellular tissues of the skin containing a large amount of melanin, outer root sheaths, hair mother cells and the like to generate Joule heat so to damage hair roots, thereby destructing a hair regeneration mechanism.
To perform the laser depilation, it is necessary to remove previously hairs subject to the depilation before laser light is irradiated so that light energy is not mostly absorbed by hairs before laser light reaches the hair roots.
Hairs are removed by various methods such as pulling out hairs using tweezers, applying depilatory cream to a target portion, peeling hairs by a depilatory tape and the like. These depilatory methods are troublesome and also involve a pain but have advantages that the finish is fine because no hair remains as compared with shaving by a razor and the regrowth of hairs is delayed.